1. Field of Invention
This invention relates to the construction of buildings and specifically to those that utilize pre-manufactured components applied to a modified post-frame type skeleton resulting in an improved building.
2. Developments in the Field
The demand for strong yet economical buildings for commercial, industrial, residential and agricultural applications has grown over the decades. In the agricultural context, barns were usually constructed of self-supporting heavy timber frames. One alternative to this construction method was the pole barn. This type of building was constructed by digging a series of holes around a perimeter of the to-be-constructed building. Long poles, such as wooden telephone or power poles, were set into the holes. Then numerous horizontal members called xe2x80x9cgirtsxe2x80x9d were then nailed to the poles increasing stability and providing a mechanism for attachment of exterior sheathing. The poles used in this method of construction were merely whole harvested timber with branches and bark removed. Consequently, the pole varied in diameter being generally wider and the base and narrower at the top. The poles, being a natural product were not uniform nor necessarily straight. This created significant problems in constructing xe2x80x9csquarexe2x80x9d buildings with true angles. This had further ramifications making the creation of properly functioning doorways and windows difficult. Since the poles narrowed and became less straight at the top, attachment of the roof rafters or trusses was difficult and sometimes irregular.
The use of poles as columns or posts in post and frame construction was supplanted by the use of standard dimensional lumber, i.e., 2xc3x974, 2xc3x976 and 2xc3x978 lumber. The regular dimensions allowed construction of truer angles. The advent of treated rot resistant lumber allowed the dimensional lumber to be inserted into foundation holes in place of poles.
3. Prior Art
The building system disclosed in U.S. Pat. No. 4,479,342 to Eberle utilizes a columnar structure wherein the lower column section sits on a pre-cast or poured concrete footing and is held in place by tamped earth. This could potentially allow wind sheer forces to lift the column from the hole thereby destroying or distorting the structure. Further, the lower section of the Eberle patent discloses a symmetrical slip joint which is inherently weaker than the staggered slip joints disclosed in this invention. The upper section of the Eberle column does not contain a center member. This requires the unnecessary step of inserting a leveling block between the upper column members to allow the insertion of a shallow heel truss. The use of a narrow-heeled truss in the Eberle patent requires the further utilization of the application of a knee brace. Utilization of deep heel trusses in this invention eliminates this particular disadvantage by providing significant stability and wind sheer resistance. Further, the Eberle building method utilizes either long girts nailed to the exterior of the sidewall columns, or girts nailed between and flush with the sidewall column lips. Utilization of individual girts instead of square and true girt panels, does not allow the columns to be plumed and leveled when the individual girts are applied. The present system allows the columns to be squared using the girt panels. The Eberle building method also discloses individual purlins which are either laid down on top of the upper truss chord or there between. The use of the individual purlins as opposed again, to a prefabricated true and plumed purlin panels does not allow the roof trusses to conform to the square and true purlin panel. Failure to use a centering column requires the user of the Eberle construction method to undertake a series of complex measurements and the use of shims in order to insure the upper ends of the upper column sections are all level.
In addition to the objects and advantages of the Post-Frame Building heretofore described, additional objects and advantages of the present invention are as follows:
(a) to reduce on site labor costs by utilizing pre-manufactured purlin and girt panel components. Through the use of jigs and machinery, the pre-manufactured girt and purlin panels are subject to higher quality control, can be manufactured to varying an exacting specifications and are manufactured with square and true angles.
(b) to increase safety by reducing the number of components needing to be assembled thereby reducing the need for workers to work atop trusses and other elevated building components.
(c) Drop in roof purlin panels provide added stability the structure during truss installation meaning more safety for the workers and less chance of damage to the structure before it is finished from severe weather (usually in the form of wind loads associated with storms).
(d) Purlin panels also help to ensure that the trusses are installed straight, plum and at the correct spacing.
(e) Purlin panels provide a more effective type of bracing for the top chord (compression chord) compared to roof purlins that are set on top of the truss. This is because the drop-in panels brace more than just the top edge of the truss top chord; they brace the depth of the chords by butting into them from both sides. This not only prevents the chords from buckling laterally (out of the plane of the truss), it also resists the torsional (twisting) mode of buckling.
(f) Deep heel trusses provides for added stability to the structure during construction. Since connection of the post to the heel is more rigid than a normal heel because the bolts or nails can be spread apart and provide a moment connection between the post and truss. In this way, this connection works like a knee brace between the post and truss.
(g) The moment connection between the post and deep heel trusses stiffens the post-truss frame and reduces lateral building deflection under wind loads.
(h) The moment connection between the post and deep heel trusses changes the moment distribution in the post and better utilizes the strength of the post.
(i) The joining of columns by the use of staggered slip joints greatly increases the column""s resistance to wind sheer.
(j) The use of a center column in the upper column section greatly reduces time needed to measure and shim, a disadvantage of the prior art.
(k) The use of purlin hangers allows the purlin panels to self position themselves and allows faster and more accurate attachment to roof trusses.
(l) Utilization of prefabricated ceiling panels attached in between the lower cords of roof trusses provides additional stability and resistance to twisting and buckling.